| 摘要: | 本論文主要針對利用氮化鋁鎵／氮化鎵異質結構成長於氮化鎵基板來製作垂直型蕭特基二極體，為了改善傳統蕭特基二極體的高導通電壓(VON)以及高漏電流問題，本次實驗加入p型氮化鎵形成p-n空乏區，達成常關型(normally-off)的操作，降低了漏電流。再藉由陽極蝕刻，蝕刻深度超過2DEG介面來降低導通電壓，並且設計陽極為T型，緩和陽極邊緣電場，提升崩潰電壓。首先，透過Silvaco TCAD模擬軟體分析無陽極蝕刻以及陽極蝕刻深度至超過2DEG介面之基本電性，其後討論製程結果之特性表現。
在室溫下量測電容-電壓曲線分析漂移層的濃度，以及順向、逆向電流-電壓特性，其中無陽極蝕刻之氮化鋁鎵/氮化鎵蕭特基二極體的導通電壓為4.05 V，當陽極蝕刻深度超過2DEG介面時，其導通電壓達到最低0.68 V，以及最小導通電阻為32 mΩ·cm2，崩潰電壓為400 V，Figure of Merit經由計算為5.0 MW/cm2。而在無陽極蝕刻加入場電板的設計，其設計延伸長度為5到10 ?m，場電板延伸長度為10 ?m的二極體，崩潰電壓提升到720 V。並且利用變溫來探討氮化鋁鎵/氮化鎵蕭特基二極體順向偏壓及逆向偏壓的特性分析，在順向偏壓下，藉由蕭特基不均勻能障模型來計算蕭特基能障，排除金屬沉積後的蕭特基接觸不均勻接面，再來利用逆向偏壓的特性曲線來進一步討論漏電流的機制。
;The thesis mainly focuses on the use of aluminum gallium nitride/gallium nitride heterostructures grown on gallium nitride substrates to make vertical Schottky diodes, in order to improve the high on-voltage (VON) and high leakage current of conventional Schottky diodes . In this experiment, p-type gallium nitride was added to form a pn depletion region, achieving a normally-off operation and reducing leakage current. Then by anode etching, the etching depth exceeds the 2DEG interface to reduce the turn on voltage, and the anode is designed to be T-shaped to relax the anode edge electric field and increase the breakdown voltage. First of all, Silvaco TCAD was used to simulate the electrical properties of schottky barrier diodes without anode recess and with anode recess on the different epitaxial layers, and then discuss the characteristics of the process results.
Measure the capacitance-voltage curve at room temperature to analyze the concentration of the drift layer, as well as the forward and reverse current-voltage characteristics. The turn on voltage of the aluminum gallium nitride/gallium nitride schottky diode without anode etching is 4.05 V, when the anode etching depth exceeds the 2DEG interface, the turn on voltage reaches the lowest 0.68 V, and the minimum on-resistance is 32 mΩ·cm2, the breakdown voltage is 400 V, and the figure of merit is calculated to be 5.0 MW/cm2. Device A is added to the design of the field plate, and its designed extension length is 5 to 10 ?m. The field plate extends the diode with a length of 10 ?m, and the breakdown voltage is increased to 720 V.
Furthermore, use variable temperature to explore the characteristics analysis of the forward bias and reverse bias of the aluminum gallium nitride/gallium nitride schottky diode. Under the forward bias, the Schottky inhomogeneous barrier model is used to calculate the schottky barrier eliminates the uneven junction of Schottky contact after metal deposition, and then uses the reverse bias characteristic curve to further discuss the leakage current mechanism. |
